feat: support retrying failed requests

[btrautmann]

📰 Summary of changes

What is the new functionality added in this PR?

This PR adds support for retrying failed network requests. In short, the following is now possible:

• Specifying a RetryBehavior "globally" for any request made by the SturdyHttp instance
• Specifying a RetryBehavior "locally" for a single request, which takes precedence over the RetryBehavior of the SturdyHttp instance
• Relying on the default retry logic provided by defaultRetryClause
• Specifying custom retry logic

Notable: This implementation does not rely on Interceptors to handle the actual retry logic as I personally have found retry logic via Interceptors to be problematic in the past. This could be changed if we find the implementation as written to not be satisfactory.

🧪 Testing done

What testing was added to cover the functionality added in this PR

Unit tests added and passing

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 58.82353% with 56 lines in your changes are missing coverage. Please review.

Project coverage is 31.46%. Comparing base (141820e) to head (1301489).

Files	Patch %	Lines
lib/src/network_response.freezed.dart	20.00%	36 Missing ⚠️
lib/src/sturdy_http_event_listener.freezed.dart	20.00%	12 Missing ⚠️
lib/src/network_request.freezed.dart	33.33%	4 Missing ⚠️
lib/src/retry_behavior.dart	83.33%	2 Missing ⚠️
lib/src/sturdy_http.dart	96.55%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main       #8      +/-   ##
==========================================
+ Coverage   29.25%   31.46%   +2.21%     
==========================================
  Files           9       10       +1     
  Lines         670      696      +26     
==========================================
+ Hits          196      219      +23     
- Misses        474      477       +3     

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[btrautmann]

/no-platform

[ClaireDavis]

this makes a lot of sense to me!

domain lgtm

[ClaireDavis]

domain lgtm